Oracle9iAS Portal Developer Kit
A Primer on the PDK-Java Provider Framework

In the portal architecture, the portal never talks to a portlet directly. It uses an interface to an entity we call a provider that represents and manages the portlets. A provider is an entity that owns portlets. Oracle9iAS Portal uses the provider to "provide" all the information for owned portlets and drive portlet operations. The provider is the communication link between the Oracle9iAS Portal and portlets.

There are two main types of provider interfaces - Database or Web. The provider interface refers to the Implementation Style. When registering a provider, you select either "Database" or "Web" as the Implementation Style. A database provider is one that is written as a stored procedure. It is installed in the Portal. Oracle9iAS Portal communicates to the database provider by making local procedure calls.

A Web provider is one that is written as a application. It is installed and hosted in a Web server and is remote from the Oracle9iAS Portal. The Portal communicates to the Web Provider using the HTTP protocol.

Because they are Web applications, Web providers are good for integrating external information sources (e.g. internet news / business information), legacy applications, and in development shops with extensive Web development backgrounds. They eliminate the need to re-create Web sites and allow development in JSP, servlets, and static files. Web providers also offer the same features as the database providers such as customization, security, etc.

One benefit of basing Web Provider communication on HTTP is that the provider implementer can develop in any HTTP server supported Web application language or runtime. For example, a Web Provider can be implemented as a cgi-bin program, a Perl script, a Java servlet or JSP, or a Microsoft ASP. The drawback of this increased flexibility is increased complexity. Except when the Oracle9iAS Portal requests a portlet to render itself into a page, prtal communication is primarily procedural (call/return).

To support Web Providers, Oracle9iAS Portal has had to define a syntax for representing the calls and returns that can be represented in an HTTP message. As this syntax is different from the normal request and response made by browsers to retrieve content, the above named (language) runtimes provide little support for processing the requests. To simplify developing Java Web Providers, the Oracle9iAS Portal Developer Kit includes PDK-Java ( JPDK). This article describes the PDK-Java, its architecture, and how it is used to develop Java-based portlets.

ARCHITECTURE

The Provider is the primary communication link between the Oracle9iAS Portal framework and portlets. The Web provider is a reference that Oracle9iAS Portal uses to locate and gather information on portlets stored externally.

If, for example, you have a Website that is comprised of Java Server Pages (JSP) or HTML, you may not want to write a database provider to mediate between Oracle9iAS and these "Web" portlets. Instead it will commonly be more convenient to implement this provider using the same runtime as the portlets. For Java developers, the PDK-Java (JPDK) simplify the process.

The main purpose of the JPDK is to provide a framework that simplifies implementation while
representing the Provider architecture in a natural way to the Java developer. The JPDK is composed of four functional areas:

For more information and in-depth descriptions of these pieces refer to the following articles:

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